The only thing I had to buy for this gun was the ball vavle. My chamber is a 12" x 1-1/2" sch40 and my barrel is 7-1/2" x 1/2" sch(something it fits in the 1/2" sch40 fittings and fits a paintball). The U is made of a 1" 90 degree elbow and inch of 1" sch40 and a 1/2" 90 degree elbow. I pressurize it using a shrader valve (I got it at Napa ask for an Industrial Tank Valve). This think packs a punch at 50 psi shooting semi frozen paintballs. I brought it up to 70 psi and then my bike pump kills itself meaning it won't go past that.